Question

. A closed, nonreactive system contains species 1 and 2 in vapor/liquid equilibrium. Species 2 is a very light gas, essentially insoluble in the liquid phase. The vapor phase contains both species 1 and 2. Some additional moles of species 2 are added to the system, which is then restored to its initial T and P. As a result of the process, does the total number of moles of liquid increase, decreases, or remain unchanged? Please consider the question using phase law.

Answer 1

The system contains species 1 & 2 out of which species 2 is very light gas & is essentially insoluble but when we add species 2 into the system the vapor liquid equillibrium will disturb and according to the question as system is restored to its original T and P so chemical potential will becomes same & Hence The liquid will increase because its in phase equilibrium with the liquid, since you added an excess of gas, some of that gas will change to liquid to preserve the eqilibrium, thus slightly increaseing the level of liquid .